This is an update of a message sent hours ago, that has yet to make it to the list. I observed the recently launched NOSS 3-4 pair, after a 23 day period without observations: 31701 07 027A 2701 G 20070712084530620 17 25 0127403-104836 47 S 31708 07 027C 2701 G 20070712084605500 17 25 0127030-104260 87 S IOD format: http://www.satobs.org/position/IODformat.html Site 2701: 43.68764 N, 79.39243 W, 230 m Assuming they have not traded places, the A object, which was the leader, was 198 s late, and about 0.08 deg higher in track than predicted by my 23 day old elements, listed below. The C object was 118 s late, and 0.1 deg higher than predicted. The track differences take into account Earth's rotation in the interim of the prediction time error. C trailed A by about 35 s. NOSS 3-4 (A) 0.0 0.0 0.0 4.9 v 1 31701U 07027A 07170.06979759 .00000020 00000-0 20000-4 0 06 2 31701 63.3811 37.1588 0232911 148.8868 212.6203 13.65676455 03 NOSS 3-4 (C) 0.0 0.0 0.0 4.9 v 1 31708U 07027C 07170.06992739 .00000020 00000-0 20000-4 0 06 2 31708 63.3479 37.1783 0231929 151.1831 210.2249 13.65605473 08 Below are estimated NOSS 3-4 elements, based on the hunch that both satellites have manoeuvred once since last observed on June 19, by Scott Campbell, mainly to achieve station-keeping. During Scott's obs of June 19, they were separated by some 15 s, compared with 34.88 s during my obs. Their orbits of June 19 would have resulted in approximately the separation I observed, by June 24, near 09:00 UTC. Assuming they manoeuvred at the nearest apogee, around 09:48 UTC, to slightly raise their perigee and nearly match mean motion, I obtain the following approximate elements: 1 71701U 07175.40826389 .00000020 00000-0 20000-4 0 07 2 71701 63.3811 22.9394 0232000 148.9211 178.8500 13.65502500 08 1 71708U 07175.40913194 .00000020 00000-0 20000-4 0 05 2 71708 63.3479 22.9423 0231400 151.2542 178.7500 13.65501000 08 Basically, I precessed my June 19 elements to the above epochs, and then adjusted mean motion by trial and error to closely predict the passes I observed this morning. I also adjusted eccentricity to hold the apogee distance constant. That nearly identical mean motions result, tends to support my hunch. If it is correct, then the above should be accurate to within a few seconds, and reasonably close in track, within 24 h of my obs of this morning. Ted Molczan ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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